Script that revealed OOM condition due to memory leak

index.php

<?php

ini_set('memory_limit', '1G');

function useAllMemory() {
	echo "Initial memory limit: " . ini_get( 'memory_limit' ) . '<br>';
	echo "Initial memory usage: " . (memory_get_usage()/(1024*1024)) . ' MB <br>';
	echo "<br>";

	$data = '';
	$counter = 0;
	$total_strlen = 0;
	$tail = str_repeat('a', 64 * 1024); // Increase string size by 64KB in each iteration
	for ($counter = 0; $counter < 1000; $counter++) {
		$data .= $tail;

		$usage = memory_get_usage();
		$real_usage = memory_get_usage(true);
		$strlen = strlen($data);
		$total_strlen += $strlen;
		echo "* iteration: $counter <br>";
		echo "* strlen(): " . ($strlen/(1024*1024)) . " MB <br>";
		echo "* memory_get_usage(false): " . ($usage/(1024*1024)) . " MB <br>";
		echo "* memory_get_usage(true): " . ($real_usage/(1024*1024)) . " MB <br>";
		echo "* aggregate strlen()'s: " . ($total_strlen/(1024*1024)) . " MB <br>";
		echo "<br>";
	}
}
useAllMemory();
die();